1. Field of the Invention
Example embodiments relate generally to nuclear reactors, and more particularly to a method and apparatus for a Boiling Water Reactor (BWR) jet pump inlet-mixer integral slip joint clamp used to constrain the inlet mixer and diffuser to mitigate inlet mixer flow induced vibrations of a BWR jet pump assembly.
2. Related Art
A reactor pressure vessel (RPV) of a boiling water reactor (BWR) typically has a generally cylindrical shape and is closed at both ends (for example by a bottom head and a removable top head). A top guide typically is spaced above a core plate within the RPV. A core shroud, or shroud, typically surrounds the core and is supported by a shroud support structure. Particularly, the shroud has a generally cylindrical shape and surrounds both the core plate and the top guide. There is a space or annulus between the cylindrical reactor pressure vessel and the cylindrically shaped shroud.
In a BWR, hollow tubular jet pumps positioned within the shroud annulus provide the required reactor core water flow. The upper portion of the jet pump, known as the inlet mixer, is laterally positioned and may be supported by conventional jet pump restrainer brackets. While conventional jet pump restrainer brackets may provide system stiffness that mitigates vibration of system components, inlet mixer slip joint flow induced vibration (SJFIV) may still occur between the inlet mixers and the diffusers. Inlet mixer SJFIV causes high vibratory loads during jet pump assembly operation which may be a major cause of jet pump wear issues.
Conventionally, many attempts have been made to reduce inlet mixer FIV. For instance, auxiliary wedges at the set screws of restrainer brackets, labyrinth seals, restrainer bracket pad repair, and replacement main wedges have all been used. While these conventional solutions have provided some additional system stiffness, none of the solutions mitigate the vibration occurring at the actual interface between the inlet mixer and the diffuser.